AppleScript code to set the theme of a JetBrains IDE, in my case CLion. I use this with an Automator Action to change to Dark/Light Mode in macOS Mojave and change the CLion theme at the same time. The code in action: https://streamable.com/0wrvn

AppleScript: set theme of JetBrains IDEs (CLion, IntelliJ)

on run {input, parameters}
	
	tell application "System Events" to set frontmost of process "CLion" to true
	
	tell application "System Events"
		tell process "CLion"
			-- close the preferences window if it's open
			key code 53 -- esc
			delay 0.5
			
			-- open the preferences window
			keystroke "," using {command down}
			delay 0.5
			
			-- search for "theme"
			keystroke "theme"
			delay 2.0
			
			-- select the first entry of the search results using the up key,
			-- and then using the down key to navigate to the "Appearance" entry
			repeat 2 times -- the search results only have 3 entries
				key code 126 -- up
				delay 0.5
			end repeat
			key code 125 -- down
			delay 0.5
			
			-- press enter to select the Themes dropdown
			key code 36 -- enter
			delay 0.5
			
			-- press space to open the dropdown
			key code 49 -- space
			delay 0.5
			
			-- press up to select the "Light" theme (use down/125 to select "Darcula")
			key code 126 -- up
			delay 0.5
			
			-- press enter to close the dropdown
			key code 36 -- enter
			delay 0.5
			
			-- press enter to apply the new settings
			key code 36 -- enter
		end tell
	end tell
	
	return input
end run